MPAACS: Magnesium for the Prevention of Atrial Arrhythmias After Cardiac Surgery

University of British Columbia

Status and phase

Terminated

Phase 3

Conditions

Coronary Artery Disease

Valvular Heart Disease

Treatments

Drug: intravenous magnesium

Study type

Interventional

Funder types

Other

Identifiers

NCT00250965

20R20015

Details and patient eligibility

About

The objective of our research is to determine whether treatment with magnesium will reduce the incidence of atrial fibrillation in patients undergoing cardiac surgery. Several small studies of magnesium have already been conducted, but these studies were small and the results conflicting. A large, well-conducted study of magnesium treatment is required to definitively determine whether magnesium is effective in preventing this common complication after surgery. In addition, our study will include patients undergoing valvular surgery, a group previously excluded from research despite the fact that they are at increased risk of atrial fibrillation.

Full description

All patients referred for non-emergent cardiac surgery for isolated CABG, isolated valvular heart surgery, or combined valvular and CABG surgery are eligible for the study. Subjects will be randomized prior to surgery (1:1) to receive 5 g magnesium or placebo (saline) bolus by the anaesthesiologist upon removal of the crossclamp. On postoperative days 1 through 4, subjects will receive either IV MgSO4 (5g in 250 ml normal saline) or IV placebo (250 ml normal saline) infusion over 4 hours daily. Atrial fibrillation (and other arrhythmias) will be detected by placing all subjects on continuous 24-hour ECG telemetry monitoring for postoperative days 0 through 4.

The study is powered to detect at least a 30% relative reduction in postoperative atrial fibrillation in the CABG group; n=756. Because of the higher incidence of atrial fibrillation in the Valve +/- CABG group a total of 500 patients will be required to detect at least a 30% difference between treatment groups. These sample sizes are based on an alpha of 0.05 and 80% power.

Enrollment

927 patients

Sex

All

Ages

20+ years old

Volunteers

No Healthy Volunteers

Inclusion criteria

patient undergoing coronary artery bypass surgery with or without valve procedure
scheduled for on-pump or cardiopulmonary bypass protocol

Exclusion criteria

existing atrial fibrillation/flutter in the past year or on antiarrhythmic medications
ventricular fibrillation
sustained ventricular tachycardia
2nd or 3rd degree heart block
paroxysmal supraventricular tachycardia
major aortic repair planned during open-heart procedure
permanent atrial/ventricular pacemaker implanted
dialysis dependent or creatinine clearance < 35 umoles/min or oliguric/anuric renal failure
patient intolerant of beta blockers
patient has reactive airways disease dependent on regular beta-adrenergic agents
patient is scheduled to undergo off-pump surgical protocol